Treatment of polyamide filaments



Dec. 8, 1964 v. v. SKEEN ETAL 3,160,511

TREATMENT OF POLYAMIDE FILAMENTS Filed June 9. 1960 I PREPARATION OF AN AQUEOUS EMULSION OF A PARTICULAR CLASS OF TRIGLYCERIDES IMPREGNATION OF UNDRAWN NYLON FILAMENTS WITH SAID EMULSION STRETCHING OF THE THUS-IMPREGNATED FILA- MENTS TO INCREASE THEMOLECULAR ORIENTATION THEREOF INVENTCRS VIRGINIA V. SKEEN BY CALVIN J. WAITKUS ,JWWLTW ATTORNEY United States Patent 3 led Sill Tamra/inter or rorizarvman nrrAMnntrs Virginia V. i-zeen, Decatur, Alan, and Calvin J. Waitlzus, ltlountain Lake, Nl, ussignors, hy mesne assignments, to Monsanto tlompeny, a corporation of Delaware .Zune 9, that), filer. No. 34,863 tllairns. (Cl. fil h-7) This invention relates to the treatment of polyarnide filaments. More particularly, it relates to new and useful compositions for use in imparting valuable properties to polyarnide filaments, a method for producing and applying the same and polyamide filaments impregnated with the said compositions.

Nylon filaments have made a substantial penetration into the tire cord market and other markets of similar rubber-fabric composite articles. In the main, the entry of nylon filaments in these fields of applications has been at the expense of .cellulosic filaments and resulted because of the many superior physical properties of nylon filaments. At present virtually all airplane and large off-theroad equipment tires are reinforced with nylon cord. Furthermore, a substantial portion of replacement passenger tires today contain nylon cord. Noteworthy is the fact that virtually all of the premium passenger car tires are reinforced with nylon cord.

One of the former drawbacks to the use of nylon cordcontaining tires was the tendency of such tires to increase undesirably in size during normal use conditions. However, during the past few years hot-stretch processes and apparatus have been developed and used to reduce the growth tendency of nylon cord tires significantly. These means have eliminated to a great degree the problem of tire dimensional growth. Another drawback of nylon cord-containing tires at a time past was the somewhat low rubber-to-cord adhesion. This latter problem has been solved by the use of certain bonding agents applied to the nylon cord prior to the time the nylon cord is incorporated in the ruober. Unfortunately, the hot-stretch filaments.

Most, if not all, of the nylon filaments today are manufactured by the melt spinning process. In such process the nylon polymer is heated to the molten or plastic state 7 but below the decomposition temperature thereof. .The

molten or plastic mass is extruded at a constant rate and under pressure through small orifices in the face of a spinneret to form molten streams of polymer. The molten polymer streams are cooled and solidified into individual filaments. The filaments are then brought together, and a finish composition is applied to the filaments. At this stage in their production the nylon filaments are not highly oriented and have relatively low tensile strength. To orient the nylon filaments and thereby to increase greatly the strength thereof, they are stretched in one or more stages to a desired extent by attenuating them by means of thread advancing devices such as two godets operated at a predetermined speed differential therebetween. It is quite advantageous to localize the point of drawing by the employment of a yarn braking device, for example, a snubbing pin, located between the godets. In one hotstretching procedure, the nylon filaments while traveling" between the snubbing pin and second godetare heated, such as by passing them across the surface of a heater At this point the deterioration of the known finishing complate maintained at a suitable elevated temperature.

positions is manifest by the visible, offensive smoking and filming of the compositions, giving rise to very serious processing problems. After being hot-stretched the filaments are collected, twisted; and a plurality of ends are plied intocord. Before being incorporated in rubber, the nylon cord usually is passed through a hot-dip bath con-.

taining a dispersion of latex and a bonding agent such as a mixture of a dihydric benzene and formaldehyde. The

thus impregnated, cord is stretched a relatively small ex tent and dried under tension. Prior art finishing compositions for nylon filaments tend to induce foaming of the hot-dip bath.

An object of this invention is the provision of an improved finishing composition for the treatment of textilematerials, such as nylon filaments, to render the same more tractable in textile operations.

Another object of this invention is the provision of a heat stable conditioning agent for treatin nylon filaments to render same more tractable in hot-stretching and for use in rubber reinforcing. V

A further object of the invention is to provide a method for the preparation of the aforesaid improved finishing According to this invention there isprepared a new and useful composition comprising an aqueous emulsion of a particular class of fatty acid esters defined below or a mixture of such esters in the presence of'a suitable emulsifying agent. Nylon filaments are impregnated therewith and the impregnated filaments are dried. Advantageously the impregnation is carried out during the manufacture of the filaments and prior to the stage in their manufacture at which they are stretched to impart increased molecular orientation therein. The impregnated filaments are rendered more tractable in textile handling operations and particularly can be effectually hot-stretched at elevated temperatures of above C. but below the sticking point of the filaments. \Vhen incorporated in rubber art-i cles for reinforcing the same, the articles exhibit high fiexural strength and accordingly have a longer service life. The improvement is especially noteworthy where the article is repeatedly flexed under elevated temperature conditions, as a pneumatic tire would be during use.

The accompanying flow diagram is given in order that an understanding of the method of the present invention can be better facilitated.

The class of fatty acid esters employed in the practice of the instant invention are mixed triglycerides and can be represented generally by the following formula:

RC OOCHz I R C 0 0 CH wherein R designates saturated or unsaturated aliphatic radicals. Two of the aliphatic radicals contain 1 to 5 car bon atoms and at most one ethylene unsaturation. The

other aliphatic radical contains 12 to 22 carbon atoms and from 0 to 5 double carbon to carbon bonds. The lower Patented Dec. 8, 1964 i acyl groups may be located in a, [3, or a, 7 positions with respect to the glyceryl radical, the location of the respective acyl groups not being critical to the present invention. Among these defined esters or mixed triglycerides are diaceto-laurin, diaceto-myristin, diaceto-palmitin, diaceto-stearin, diaceto-arachidin, diaceto-behenin, diaceto-lignocerin, diaceto-laurolein, diaceto-myristolein, diaceto-palmitolein, diaceto-olein, diaceto-gadolein, diaceto-erucin, diaceto ricinolein, diaceto-linolein, diaceto-linolenin, diaceto-elaeostearin, diaceto-licanin, diaceto-arachidonin, and diaceto-clupanodonin.

Of the just mentioned triglycerides the preferred com pounds are diaceto-ricinolein, diaceto-linolein, and diacetolinolenin, as well as mixtures of these three compounds. As indicated above the lower fatty acid substituents can be either in the alpha, beta, or the alpha, gamma positions. I

Other suitable triglycerides include dipropiono-laurin, dipropiono-myristin, dipropiono-palmitin, dipropiono-stearin, dipropiono-arachidin, dipropiono-behenin, dipropiono-lignocerin, dipropiono-laurol'ein, dipropiono-myristolein, dipropiono-palmitolein, dipropiono-olein, dipropiono gadolein, dipropiono-erucin, dipropiono-ricinolein, dipropiono-linolein, dipropiono-linolenin, dipropiono-elaeostearin, dipropiono-licanin, dipropiono-arachidonin, and dipropiono-clupanodonin;

divalero-stearin, divaler-o-arachidin, divalero-behenin, divalero-lignocerin, divalero-laurolein, divalero-myristolein, divalero-palmitolein, divalero-olein, divalero-gadolein, divalero-erucin, divalero-ricinolein, divalero-linolein, divalero-linolenin, divalero-elaeostearin, divalero-licanin, divalero-arachidonin, and divalero-clupanodonin;

dicapro-laurin, dicapro-myristin, dicapro-palmitin, dicapro-stearin, dicaproarachidin, dicapro-behenin, dicapro-lignocerin, dicapro-laurolein, dicapro-myristolein, dicapro-palmitolein, dicapro-olein,

dicapro-gadolein, dicapro-erucin, dicapro-ricinolein, dicapro-linolein, dicapro-linolenin, dicapro-elaeostearin, dicapro-lieanin, dicapro-arachidonin, and dicapro-clupanod0nin;

dicrotono-laurin, dicrotono-myristin, dicrotonorpalmitin, dicrotono-stearin, dicrotono-arachidin, dicrotono-behenin,

1 dicrotono-lignocerin, dicrotonoJ-aurolein, dicrotono-myristolein, dicrotono-palmitolein, dicrotono-olein, dicrotono-gadolein, dicrotono-erucin, dicrotono-ricinolein, dicrotono-linolein, dicrotono-linolenin, dicrotono-elaeostearin, dicrotono-licanin, dicrotono-anachidonin, and

' dicrotono-clupanodonin and others corresponding to the above structural formula. In general, methods for producing these mixed triglycerides are known and involve conventional tri-esterification of glycerol with the selected fatty acids.

The finishing composition of the present invention is an aqueous emulsion, and hence a suitable emulsifying agent normally is employed as an ingredient thereof for I rendering the emulsion more stable. While a number of emulsifying agents can be employed and are within the scope of the general disclosure, the nonionic surfacelactive agents are the preferred class of materials. Of the nonionic surface active agents the polyethers are the preferred emulsifying agents, including :alkylaryl polyoxyethylene ethanols, alkyl polyoxyethylene ethanols, alkylaryl poly.- oxypropylene ethanols, alkyl polyoxypropylene ethanols, etc. 7 In general these polyether compounds are prepared by reacting a suitable monohydric or polyhydric alcohol with suitable amounts of alkylene oxide. Ethylene oxide is the most often used alkylene oxide in view of its attractive price, but propylene oxide may be used in whole or in part with ethylene oxide.

Suitable primary alcohols reactable with ethylene oxide and the like for preparing the emulsifying agents employed herein include dodecyl alcohol, myristyl alcohol, cetyl, alcohol, stearyl alcohol, palmitoleyl alcohol, oleyl alcohol, linoleyl alcohol, carnaubyl alcohol and others. The long chain aliphatic radical of these alcohols may have from -24 and higher carbon atoms in the chain and 0 to 2 double bonded carbons. The preferred alcohols are C -C compounds. The primary alcohols of the just described type are condensed with 5 to moles of ethylene oxide or like alkylene oxide.

As indicated alkylaryl polyoxyalkylene alcohols are also 1 useful as emulsir" in a ents. These com ounds are enerally prepared by reacting 8 to 30 moles of an alkylene oxide such as ethylene oxide with alkyl substituted phenols. The alkyl group or groups substituted on the benzene ring contain 2 to 20 carbon atoms in each chain and preferably from 5 to 7 carbon atoms. Trade names of these alkylaryl polyoxyalkylene alcohols include lgepol CA, Igepol #300, lgepol CO, Antarox A-400, Triton X10, Emulphor DDT, and are believed to have the formula:

Colin Suitable polyhydric alcohols condensed with alkylene oxide include, for example, sorbitan monolaurate polyoxyethylene condensate (20 moles of ethylene oxide), sorbi tan monopalmitate polyoxyethylene condensate moles of ethylene oxide), sorbitan monostearate polyoxyethylene condensate (60 moles of ethylene oxide), sorbitan monooleate polyoxyethylene condensate (80 moles of ethylene oxide), and the like. Again the pre- Iferred alkylene oxide is ethylene oxide, however as previously indicated, propylene oxide is known to be an equivalent therefor in some instances.

The ratio of emulsifying agent to the triglyceride ester component can be varied within rather wide limits, the requirement being that enough emulsifying agent be employed so that the emulsion is stable. However, it has been found that in order to prepare stable emulsions of the esters above defined and essential to the present composition, the percentage of emulsifying agent, based on the weight of the ester plus the emulsifying agent, can be about 10 percent to about percent. The preferred percentage is about 30 to about 40 percent by weight.

In order to obtain the benefits of the treatment of this invention, it is generally necessary that the triglyceride compound remain in or on the nylon filaments at the time the filaments are hot-stretched and at the time they are employed in a rubber composite article in an amount from about 0.05 to about 3.0 percent based on the weight of the filaments,

For convenience, the finishing composition of the sent invention is applied to a longitudinally traveling bundle of filaments by employment of :a roller partly immersed in the composition or a wick material partly immersed in the composition, the traveling filaments coming into contact therewith. In place of such manner of application, the finishing composition can be impregnated in the nylon filaments in any other suitable manner, such as by immersion in a bath of the composition or by spraying or brushing the composition on the filaments.

The relative concentration of the triglyceride ester component in the finishing composition can be varied considerably in obtaining impregnation of the ester on the filaments in the above-mentioned amounts. The concentration will depend, among 0 er things, on the particular method of impregnation employed, and on the form of filaments treated. Emulsions ranging from about 0.5 to

about 20 percent or'higher of the triglyceride ester component based on the weight of the finishing composition are quite suitable for impregnating commercial nylon filaments.

The new and useful filament finishing composition can be prepared in the following manner. The selected triglyceride ester component and emulsifying agent therefor are intimately agitated together with the desired quantity of water at temperatures of about 25 C. to 50 C. In

one excellent way of preparing an emulsion of good stability, the ingredients are agitated in a high shear liquid blender or mill, such as a Waring Blender. Generally, an agitation time of about 5 to 30 minutes at temperatures from 0 to C. is sufficient to prepare emulsions exhibiting good stability. It is preferred, however, that the new finishing compositions be prepared by blending the triglyceride component with the emulsifying agent ata temperature of about 40 C. to 45 C., subsequently adding the required amount of water and thereafter vigorously agitating the emulsion for about 20 to 30 minutes at about 15 C. to 30 C. Where desirable, the emulsion is cooled by suitable means during the agitation period.

Nylon, as is Well known, is a high molecular weight l'mear polymer which contains recurring. carbonamide groups as an integral part of the main polymer chain separated by at least two carbon atoms. Broadly speaking, nylon polymers are of two general types. One type of nylon is obtainable from polymerizable monoaminomono carboxylic acids and their amide-forming derivatives, for example e-caprolactam and a-pyrrolidone, known generically in their polymerized form as nylon-6 and nylon- 4, respectively. The other type of commercial nylon is obtainable from suitable primary or secondary diamines and suitable dicarboxylic acids or amide-forming derivatives thereof. Among the latter type are polymers formed by the reaction of tetramethylene diamine, pentamethylene diamine, hexamethylene diamine and the like with adipic acid, suberic acid, sebacic acid and the like. The polymerization product of hexamethylene di-amine and adipic acid has the generic name of nylon-66 The manner in which the foregoing aspects of the invention are attained will appear more fully from the following example, in which reference is made to typical and preferred procedures in order to indicate more fully the nature to the invention, but without intending to limit the invention thereby. In the example all parts and per centages are by weight unless otherwise indicated.

Example Eighteen parts of diaceto-ricinolein was combined with 2 parts of an emulsifier composed of a mixture of myiistyl alcohol, cetylalco'nol, stearyl alcohol, arachyl alcohol, palmitoleyl alcohol, oleyl alcohol, and linoleyl alcohol having been condensed with 20 moles of ethylene oxide per mole of alcohol. The mixture of triglyceride ester component and emulsifying agent was homogenized with 180 parts of water to form a stable emulsion. The emulsion was applied to a bundle or nylon-66 filaments having an ultimate total denier of 840 between the spinneret employed in the melt-spinning of the filaments and the point of first take-up in an orderly manner on a spin bobbin. The filaments were hot drawn on a conventional draw-twist machine employing two sets of rolls, a drawing pin in the yarn path between said rolls, a heated plate in the yarn path between said pin and said second set of rolls, and a ring twister take-up assembly. Between the two sets of rolls, the filaments are stretched about 5 times. The filaments attained a temperature of about C. during the operation.

The finishing composition showed no signs of decomposition and was completely stable at the temperature employed.

When a finished heretofore known and composed in the main of sulfonated peanut oil and mineral oil was applied to the filaments in the same manner as stated above in place of the triglyceride ester, offensive smoke and fumes were given off during the processing.

The filaments containing the novel finishing composition and those containing the heretofore known finish were separately processed into tire cord, and the cord incorporated into a pneumatic tire by standard and conventional procedures. The nylon filament cord containing the triglyceride ingredient processed well in the hot-dip bath and exhibited improved and more uniform adhesion characteristics with resect to the rubber of the tire as .compared with cord containing the heretofore known composition. The nylon filament cords were used as the reinforcing textile fabrics in pneumatic tires by standard procedure. The tires were of the type used in high speed racing vehicles. Tire failure occurred in the tires containing the heretofore known finish long before failure occurred in the tires impregnated with the triglyceride ingredient.

When other triglyceride ester materials of the defined class are emulsified with other non-ionic emulsifying agents, similarly excellent results are obtained in the production of nylon-66 and nylon-6 tire cord.

Thus nylon filaments treated with the new finishing compositions above described are especially adapted for use in the rubber-fabric composite articles since they may be hot-stretched efiiciently without the occurrence of obnoxious smoking and fuming. In addition to rendering the filament more amenable to hot-stretching, the new finishing compositions have numerous other advantages such as providing increased adhesion between the rubber and filaments and increased resistance of the rubber-fabric composite articles to heat deterioration upon repeated rapid flexing, as in the case of pneumatic tires.

It is to be understood that the foregoing description is given merely by way of illustration and that many variations may be made therein, without departing from the spirit of the invention. a

This application is a continuation-in-part application of copending application S.N. 797,014, filed March 4, 1959 (now abandoned).

What is claimed is:

1. A method of treating nylon filaments comprising impregnating nylon filaments of low molecular orientation with an aqueous emulsion containing a triglyceride having the structural formula:

R o 0 on,

,RCOOCH nooobn,

wherein R designates aliphatic radicals, two of which having 1 to 5 carbon atoms and at most one double carbon to carbon bond and one of which having 12 to 22 carbon atoms and at most 5 double carbon to carbon bonds, and stretching the thus impregnated filaments to increase the molecular orientation thereof, the filaments during stretching having a triglyceride content of about 0.05 to about 3.0 percent by weight.

2. The method of claim 1 wherein the stretching is carried out at an elevated temperature of above 140 C. and below the temperature at which sticking of the filaments occur.

'3. A method of treating nylon filaments comprising impregnating nylon filaments of low molecular orientation with an aqueous emulsion containing diaceto-ricinolein and stretchingthe said filaments to increasethe molecular orientation thereof, the filaments during stretching having a content of diaceto-ricinolein of about 0.05 to about 3.0 percent by weight.

4. A method of treating nylon filaments comprising impregnating nylon filaments of low' molecular orientation with an aqueous emulsion containing diaceto-linolein and stretching the said filaments to increase the molecular orientation thereof, the filaments during stretching having a content of diaceto-linolein of about 0.05 to about 3.0 percent by weight.

5. A method of treating nylon filaments comprising impregnating nylon filaments of low molecular orientation with an aqueous emulsion containing diaceto-linolenin and stretching the said filaments to increase the molecular orientation thereof, the filaments during stretching having a content of diaceto-linolenin of about0.5 to about 3.0 percent by weight.

6. The method of claim 3 wherein the stretching is carried out at an elevated temperature of above C. and below the temperature at which sticking of the filaments occur and wherein the emulsion contains a nonionic surface active emulsifying agent.

7. The method of claim 4 wherein the stretching is carried out at an elevated temperature of above 140 C. and below the temperature at which sticking of the filaments occur and wherein the emulsion contains a nonionic surface active emulsifying agent.

8. The method of claim 5 wherein the stretching is carried out at an elevated temperature of above 140 C. and below the temperature at which sticking of the filaments occur and wherein the emulsion contains a nonionie surface active emulsifying agent.

9. The method of claim 1 wherein the nylon filaments are made of a polymer selected from the group, consisting of nylon-66 and nylon-6.

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1. A METHOD OF TREATING NYLON FILAMENTS COMPRISING IMPREGNATING NYLON FILAMENTS OF LOW MOLECULAR ORIENTATION WITH AN AQUEOUS EMULSION CONTAINING A TRIGLYCERIDE HAVING THE STRUCTURAL FORMULA: R-COO-CH2-CH(-OOC-R)-CH2-OOC-R WHEREIN R DESIGNATES ALIPHATIC RADICALS, TWO OF WHICH HAVING 1 TO 5 CARBON ABOMTS AND AT MOST ONE DOUBLE CARBON TO CARBON BOND AND ONE OF WHICH HAVING 12 TO 22 CARBON ATOMS AND AT MOST 5 DOUBLE CARBON TO CARBON BONDS, AND STRETCHING THE THUS IMPREGNATED FILAMENTS TO INCREASE THE MOLECULAR ORIENTATION THEREOF, THE FILAMENTS DURING STRETCHING HAVING A TRIGLYCERIDE CONTENT OF ABOUT 0.05 TO ABOUT 3.0 PERCENT BY WEIGHT. 